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CARDIAC ARREST FROM OVERDOSE

CARDIAC ARREST FROM OVERDOSE. All patients should have: DECONTAMINATION of the GIT CORRECTION of ELECTROLYTES abnormalities CARDIOVERSION when appropriate OXYGENATION and protection of airway CONSULTATION WITH THE CLINICAL PHARMACOLOGIST

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CARDIAC ARREST FROM OVERDOSE

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  1. CARDIAC ARREST FROM OVERDOSE • All patients should have: • DECONTAMINATION of the GIT • CORRECTION of ELECTROLYTES abnormalities • CARDIOVERSION when appropriate • OXYGENATION and protection of airway • CONSULTATION WITH THE CLINICAL PHARMACOLOGIST • Successful resuscitation has been well documented after 8 hours of CPR

  2. CARDIAC ARREST FROM OVERDOSE • Overdose patients may have: • a reversible cause for their arrest • good general health • novel treatments for arrhythmias • cerebral protection

  3. CARDIAC ARREST FROM OVERDOSE • The major causes of cardiac arrhythmia in our area are: • QUINIDINE-LIKE DRUGS • SYMPATHOMIMETIC DRUGS • CALCIUM CHANNEL BLOCKERS • BETA BLOCKERS • DIGITALIS • CHLOROQUINE • Arrhythmias may also be secondary to metabolic/electrolyte abnormalities eg • salicylates, methanol, ethylene glycol

  4. QUINIDINE-LIKE DRUGS • TRICYCLIC ANTIDEPRESSANTS • PHENOTHIAZINES • QUINIDINE • PROCAINAMIDE • DISOPYRAMIDE • QUININE

  5. SYMPATHOMIMETIC DRUGS • INCREASED SENSITIVITY TO CATECHOLAMINES • CHLORAL HYDRATE • THEOPHYLLINE • INCREASED CATECHOLAMINES • AMPHETAMINES • COCAINE • THEOPHYLLINE • BETA AGONISTS • Arrhythmias normally respond to beta blockade (propranolol)

  6. CHLORAL HYDRATE OVERDOSE • Grandfather drug hypnotic 1869 • 1890 review of the first 44 deaths • death = tricyclics • Prodrug with enhanced formation of active tichloroethanol by alcohol • Rapid absorption with peak levels 0.5-1 hour • Deaths as little as 2-3 grams in adults (5-10 grams more commonly) • Recreational and inappropriate use • Trichloroethanol T1/2 between 8 to 35 hours sensitises myocardium to catecholamines.

  7. CALCIUM CHANNEL BLOCKERS • HYPOTENSION • Peripheral vasodilatation & myocardial depression • Volume expansion (normal saline) • Calcium gluconate (1-4 ampoules) • BRADYARRHYTHMIA • Ca++ (4-8 ampoules) • Adrenaline, isoprenaline, dopamine infusion • Correct acidosis if pH>7.2 • Pacemaker if 2nd degree heart block or above

  8. CHLOROQUINE • Features of toxicity may develop within 30 minutes • death may occur within 3-4 hours • myocardial depression • arrhythmia. • TOXICOKINETICS • RAPIDLY ABSORBED • DOSE DEPENDENT KINETICS

  9. CHLOROQUINE - RISK FACTORS FOR SUDDEN DEATH • Ingested > 50 mg/kg of chloroquine base • Systolic BP < 90 mmHg • QRS of > 110 msecs • Major complications • deteriorating level of consciousness • seizure • any cardiac arrhythmia.

  10. CHLOROQUINE - TREATMENT • Elective intubation and ventilation. • Diazepam 2 mg/kg over 30 minutes followed by 1-2 mg/kg/day infusion. • Adrenaline 0.25 micg/kg/hr by continuous infusion • systolic BP > 100 mmHg. • Gastric lavage followed by activated charcoal.

  11. DIGOXIN - TOXICCOKINETICS • Vd 5-7L/kg • T1/2 30-45h • peak effect 3-6h • absorption 50-80% • urinary excretion 60-80% • therapeutic level 0.6-2.0 ng/ml

  12. DIGOXIN - PATHOPHYSIOLOGY • Inhibits Na K ATPase • increased automaticity and excitability • extrasystoles • tachyarrhythmias • increased refractoriness at AV node & decreased conduction velocity throughout conduction system • AV block • bradycardia • prolonged PR interval

  13. DIGOXIN - PREDISPOSING FACTORS • DRUG INTERACTIONS • Quinidine • Calcium channel blockers • Amiodarone • Spironolactone • NSAIDs (decreased renal clearance) • Diuretics (K Mg Na HCO3)

  14. DIGOXIN - PREDISPOSING FACTORS • DISEASE STATES • electrolyte imbalance • renal failure • myocardial infarct • cor pulmonale • hypothyroidism • cardiac failure • hypoxia

  15. INDICATIONS FOR DIG Fab USE • hyperkalaemia • tachyarrhythmias (60-65% mortality) • high grade AV block • digoxin level > 15ng/ml • DOSE • equimolar : 1 vial (40mg) neutralises 0.6mg digoxin

  16. BETA BLOCKER POISONING - Mechanism of Toxicity • Block betas • hypotension • bradycardia • cardiac failure • insulin release • hypoglycaemia • bronchoconstriction (beta 2)

  17. BETA BLOCKER POISONING - Mechanism of Toxicity • Stimulate beta adrenoreceptors (partial agonist) • tachycardia • hypertension • Membrane stabilising (quinidine like) • QRS widening • cardiac conduction block, asystole

  18. BETA BLOCKER POISONING - Mechanism of Toxicity • Central Nervous system effects • coma • seizures • Class III antiarrhythmic activity (sotalol) • QT prolongation • Torsade de pointes

  19. CARDIAC CASE 1 • 18 y o woman admitted 3 hours after overdose of • 3.5gms of slow release verapamil • 6gms of paracetamol • tetracycline 4500mg • 1000 mg of pseudoephedrine • vomited before arrival

  20. CARDIAC CASE - EXAMINATION • On arrival in casualty • P 120, BP 110/80, RR 20, afebrile • Drowsy but oriented and cooperative • Other examination NAD • Lavaged with green tablets (colour of Isoptin SR) returned • 50gms of charcoal with sorbitol.

  21. CARDIAC CASE - INITIAL INVESTIGATIONS • ECG - sinus tachycardia with normal QRS width • admitted to ICU for monitoring • 4 hour serum paracetamol level was 38 nmol/L • (significant risk of hepatotoxicity > 1300nmol/L at 4 hours) • Further 50gm dose of charcoal 4 hours later

  22. CARDIAC CASE - LATER ON • 16 hours post overdose • BP fell to 70/40 and then 50/30. • P 50 • oxygen saturation dropped to 75% • ECG • absent P waves • prominent U waves • normal QRS duration and QT interval

  23. CARDIAC CASE - TREATMENT • IV atropine 0.6mgs - no response • IV calcium gluconate • 6gms over 20 minutes • further 6gms over the next hour • Following the calcium bolus • P60 sinus rhythm, BP 100/80 • oxygen saturation > 95% • Infusion of 10% calcium gluconate at 2gms an hour continued for 10 hours (total calcium gluconate dose of 30gms) • She was also given 2.5L IV fluids.

  24. CARDIAC CASE - OUTCOME • Twenty four hours post admission • Largely recovered • sinus rhythm P 60, BP 115/70 • Calcium was ceased • No further hypotension or bradycardia • Peak serum Ca was 4.8 (NR=2.18 - 2.47mmol/L) • Serial Verapamil levels at 6, 18, 22 and 46 hours were 616, 2374, 2518 and 1006 ng/ml • (range during usual therapy - 100-300 ng/ml) • Non cardiogenic pulmonary oedema

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